Apollo Backflow Preventer Selection Guide
Backflow prevention is code-required on virtually every commercial water service connection in the US. Selecting the wrong device results in failed inspection, costly replacement, and potential liability. This guide walks through the Apollo 4A Series — Reduced Pressure (RP), Double Check (DC), and Pressure Vacuum Breaker (PVB) — and tells you which device belongs on each application.
The Three Levels of Backflow Protection
Reduced Pressure Zone (RP) — Highest protection. Required for high-hazard connections where a contamination event would cause serious health risk. Two check valves with a differential pressure relief zone between them. If either check fails, the relief valve opens to atmosphere rather than allowing backflow. ASSE 1013 listed.
Double Check Valve Assembly (DC) — Medium protection. Two independent check valves in series. No relief valve. Approved for low-to-moderate hazard connections where a contamination event would be nuisance rather than health-threatening. ASSE 1015 listed.
Pressure Vacuum Breaker (PVB) — Backsiphonage protection only. A single check valve with an atmospheric vent that opens under vacuum conditions. For applications where backpressure is not present — typically irrigation above grade. ASSE 1020 listed. Cannot be used where downstream pressure can exceed supply pressure.
Which Device for Which Application
| Application | Hazard Level | Required Device |
|---|---|---|
| Boiler / hydronic heating system | High (chemical additives) | RP Assembly |
| Chemical injection / treatment | High | RP Assembly |
| Hospital / medical facility | High | RP Assembly |
| Irrigation with fertilizer injection | High | RP Assembly |
| Commercial HVAC (no additives) | Low-Medium | DC Assembly |
| Commercial building water service | Low-Medium | DC Assembly |
| Fire sprinkler (non-chemical) | Low-Medium | DC Assembly |
| Above-grade irrigation (no additives) | Low (backsiphonage only) | PVB |
Apollo 4A Series Configuration Options
The Apollo 4A Series is available with multiple isolation valve configurations to match local AHJ requirements:
- Ball Valve Isolation — Standard stainless steel handle ball valves. Most common for commercial applications.
- OS&Y Gate Valve Isolation — Outside screw and yoke gate valves. Required on some fire protection and municipal applications where valve position must be visually confirmed.
- NRS Gate Valve Isolation — Non-rising stem gate valves. For installations with limited vertical clearance.
Annual Testing Requirements
RP and DC assemblies require annual testing by a state-certified backflow tester in most jurisdictions. Maintain test records — water authorities often require test reports on file. PVBs typically require annual inspection but not full differential pressure testing. Always verify requirements with your local water authority.
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